Embodiments of the invention relate to the enclosure of an operation mechanism to actuate an indoor or outdoor circuit breaker.
To ensure reliable operation of a circuit breaker operation mechanism over many years, all mechanical parts have to be protected against water, snow, dust and the like. Furthermore, to save to protect operating personnel from injury, the enclosure has to enclose all the moving parts of the mechanism.
This mechanism comprises a main shaft which protrudes out of the enclosure, and which is connected to an actuating member of the circuit breaker.
To avoid an electric arc appearing in the circuit breaker when it is opened, the main shaft has to be rotated quickly and accurately along a predetermined rotational path. More specifically, if the electric contacts are opened at sufficient speed and at the appropriate time, the chances of appearance of an electric arc are almost zero.
For this reason, the operation mechanism comprises an actuating spring cooperating with cams and levers carried by secondary shafts, to actuate the main shaft. When the circuit is to be opened, the actuating spring is released to rotate the cams and levers carried by the secondary shaft, which in turn to rotate the main shaft at the appropriate speed along the predetermined rotational path.
With the operation being conducted in a very short time interval, the mechanical components are moved at high speed, and thus require that the mechanism be powerful.
As a result, the general structure of this type of mechanism, which can be seen for example in FIGS. 1 to 5 of patent document U.S. Pat. No. 7,227,091 is heavy. It comprises two or more supporting plates, to which are secured ball bearings carrying the main shaft and the secondary shafts, and other mechanical components.
Since this mechanism has to be protected from rain, snow and the like, it is installed into a sealed cabinet, which is made of metal sheets which are arranged together and sealed.
The aim of embodiments of the invention is to provide a solution to reduce the cost of such a system in order to render it more competitive.